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4.18.2012

Did Viking Found Life on Mars?

NASA's Curiosity rover is set to land
on Mars in August and will hunt for signs of life's potential on ancient
Mars. Some scientists still believe that the Viking mission has already
found evidence of life.

A view of the boulder-strewn field of red rocks reaches to the horizon nearly two miles from Viking 2 on Mars' Utopian Plain. Image credit: NASA

A six-inch-deep trench in the Martian soil dug by Viking 1 in February
1977. The goal was to reach a foot below the surface for sampling.
Credit: NASA

The Curiosity rover is currently on its way to Mars, scheduled to make a dramatic landing
within Gale Crater in mid-August and begin its hunt for the geologic
signatures of a watery, life-friendly past. Solid evidence that large
volumes of water existed on Mars at some point would be a major step
forward in the search for life on the Red Planet.

But has it already been found? Some scientists say yes.

Researchers from universities in Los Angeles, California, Tempe, Arizona and Siena, Italy have published a paper in the International Journal of Aeronautical and Space Sciences (IJASS) citing the results of their work with data obtained by NASA's Viking mission.

The twin Viking
1 and 2 landers, which launched in August and September of 1975,
successfully landed on Mars in July and September of the following year.
Their principal mission was to search for life, which they did by
digging into the ruddy Martian soil looking for signs of biological
activity.

The Viking Labeled Release experiment added nutrient to samples of Mars
soil, and then checked to see if microbes that may have been living in
the soil expelled any waste products. Gas was released, but scientists
could not rule out that this could have been the result of abiological
chemical reactions.

Now, 35 years later, one team of researchers claims that the Viking
landers did indeed detect life within their soil samples. Their study
looked at the time series of what happened between the moment of adding
nutrient and the release of gas, and said it was similar to what happens
when microbes living in soil on Earth take up nutrients and exhale
waste.

However, a process of conclusively identifying life has not yet been perfected - not even here on Earth.

“It’s an interesting and novel approach, but I don’t think it’s
necessarily the definitive proof of life that they are claiming,” says
Michael New, Astrobiology Discipline Scientist at NASA. “Are there
abiological processes that could also produce that same sort of signal?”

New says just because the pattern seen in the results resembles life, doesn’t necessarily mean it is life.

"In the absence of a predictive model, it's hard to say that when two
series of measurements have the same properties, they are produced by
the same phenomenon," he says.

The new study shows that questions about the old Viking data still live
on. Future missions, including Curiosity rover, will hopefully help us
find some answers about the potential for life on Mars.